Thin films are thin material layers ranging from fraction of a nanometer to multiple micrometers in thickness. Thin films are found, for example, in floor coatings, CD/DVD coatings, pressure sensitive adhesives, dental fillings, curable inks, fiber optic coatings, and contact lenses. Electronic semiconductor devices and optical coatings, for example antireflective (AR) coatings, are primary commercial applications benefiting from thin film construction, and future applications, such as thin-film batteries and computer memories are envisioned.
For many applications, such as thin film coatings, semiconductors, adhesives, biomaterials, and hydrogel systems, it is advantageous to produce a non-homogeneous film, for instance a film that has different surface and substrate interface chemistries. For example, the performance of optical coatings is typically enhanced when the thin film coating includes multiple layers having varying thicknesses and refractive indices. Similarly, a periodic structure of alternating thin films of different materials can collectively form a “superlattice” which exploits the phenomenon of quantum confinement by restricting electronic phenomena to two-dimensions.
Unfortunately, conventional methods produce a layer of thin film coating that is itself homogeneous. Accordingly, conventional methods to create non-homogeneous films include casting multiple layers or using solvent evaporation to achieve desired surface and substrate interface chemistries. While such methods can yield desired properties, they are time-consuming and may result in delamination of the product film. Thus, there remains a need for more efficient processes for producing stratified polymeric materials.